Postglacial evolution of coastal barriers along the West Pomeranian coast, NE Germany

摘要

The aim of this study is to present an evolutionary model of the coastal barriers in West Pomerania regarding both morphological development and chronostratigraphy. The study area is situated on the islands of Ruegen and Usedom in the tideless SW Baltic. To reconstruct the geological setting, 250 cores were collected; 20 new radiocarbon dates allow a description of the Late Pleistocene to Holocene evolution of the barriers. In all areas investigated, the lithofacies sequences are similar, which enables the derivation of a general evolutionary model for the SW Baltic Sea coasts. The controlling factors are the relief of the Early Holocene landscape as well as the sea-level history of the Baltic Sea. The base is made up of a Pleistocene till. The deposition of this till had already determined the configuration of the present-day coast. Late Pleistocene to Early Holocene freshwater deposits follow in the columnar section, often overlain by peat. During the main phase of the transgression (8000-6000 before present (BP)) the Early Holocene landscape was "drowned" and mud accumulated in the depressions. Beach ridges, attached to Pleistocene headlands, began to develop at 6000 BP. Simultaneously, landward of the beach ridges sediment accumulated in wind flats. This depositional environment, which can still be recognised along the coast today, is controlled by wind-driven currents. A second peat layer, younger than 1000 BP, makes up the uppermost part of the sequence in most of the lowland sites. The evolution of the coastal barriers in West Pomerania follows the scheme developed for tidal paraglacial coasts. This study adjusts the scheme to the regional stratigraphy and extends it with regard to tideless conditions and the evolution of wind flats.